This security update resolves vulnerabilities in Microsoft Windows. The more severe of the vulnerabilities could allow elevation of privilege if an attacker logs on to an affected system and runs a specially crafted application.

Note Customers who are using local and remote reporting attestation solutions should review the details of CVE-2015-2552 discussed in this bulletin.

This security update is rated Important for all supported releases of Microsoft Windows. For more information, see the Affected Software section.

The security update addresses the vulnerabilities by correcting how the Windows kernel handles objects in memory, by correcting how Windows handles certain scenarios involving junction and mount-point creation, and by improving how Windows parses Boot Configuration Data (BCD). For more information about the vulnerabilities, see the Vulnerability Information section.

The following software versions or editions are affected. Versions or editions that are not listed are either past their support life cycle or are not affected. To determine the support life cycle for your software version or edition, see Microsoft Support Lifecycle.

[2]The Windows 10 update is cumulative. In addition to containing non-security updates, it also contains all of the security fixes for all of the Windows 10-affected vulnerabilities shipping with this month’s security release. The update is available via the Windows Update Catalog. See Microsoft Knowledge Base Article 3097617 for more information and download links.

*The Updates Replaced column shows only the latest update in any chain of superseded updates. For a comprehensive list of updates replaced, go to the Microsoft Update Catalog, search for the update KB number, and then view update details (updates replaced information is provided on the Package Details tab).

Note Windows Server Technical Preview 3 is affected. Customers running this operating system are encouraged to apply the update, which is available via Windows Update.

The following severity ratings assume the potential maximum impact of the vulnerability. For information regarding the likelihood, within 30 days of this security bulletin's release, of the exploitability of the vulnerability in relation to its severity rating and security impact, please see the Exploitability Index in the October bulletin summary.

Multiple Windows Kernel Elevation of Privilege Vulnerabilities

Multiple elevation of privilege vulnerabilities exist in the way the Windows kernel handles objects in memory. An attacker who successfully exploited the vulnerabilities could run arbitrary code in kernel mode. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights.

To exploit the vulnerabilities, an attacker would first have to log on to the system. An attacker could then run a specially crafted application that could exploit the vulnerabilities and take control over an affected system. The update addresses the vulnerabilities by correcting how the Windows kernel handles objects in memory.

An attacker who has gained administrative privileges or who has physical access to a target device could exploit the vulnerability by applying a maliciously crafted Boot Configuration Data (BCD) setting. The security update addresses the vulnerability by improving how Windows parses BCD.

This vulnerability has been publicly disclosed. It has been assigned Common Vulnerability and Exposure number CVE-2015-2552. At the time this security bulletin was originally issued, Microsoft was unaware of any attack attempting to exploit this vulnerability.

Open Control Panel, click System and Security, and then click BitLocker Drive Encryption.

Click Resume protection.

Close Control Panel.

Vulnerability FAQ

Is the Device Health Attestation (DHA Report) that is generated by Microsoft Windows 10 Device Health Attestation Service (or other local or remote attestation solutions that process TCG logs, such as PCPTool) impacted by this vulnerability? Yes. Local and remote reporting attestation solutions that process measurements that are captured/logged by TPM TCG logs are impacted by this vulnerability. In a future release Microsoft will enable IT managers to detect this vulnerability remotely using the Microsoft Device Health Attestation – Cloud Service.

An elevation of privilege vulnerability exists when Windows improperly validates junctions in certain scenarios in which mount points are being created. An attacker who successfully exploited this vulnerability could potentially run arbitrary code in the security context of the user running a compromised application.

To exploit this vulnerability, an attacker would most likely have to leverage another vulnerability that allows them to run arbitrary code in a sandboxed application. The update addresses the vulnerability by correcting how Windows handles certain scenarios involving junction and mount-point creation.

This vulnerability has been publicly disclosed. It has been assigned Common Vulnerability and Exposure number CVE-2015-2553. At the time this security bulletin was originally issued, Microsoft was unaware of any attack attempting to exploit this vulnerability.

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V1.1 (October 16, 2015): Bulletin revised to announce a detection change in the 3097617 cumulative update for Windows 10. This is a detection change only. Customers who have already successfully updated their systems do not need to take any action.

V1.2 (October 29, 2015): Bulletin revised to announce a detection change in the 3088195 update for all supported editions of Windows 7, Windows Server 2008 R2, Windows 8, Windows Server 2012, Windows RT, Windows 8.1, Windows Server 2012 R2, and Windows RT 8.1. The detection change temporarily blocks deployment of the 3088195 update to systems running a specific version of USB Blocker software that is incompatible with the update. For more information, see Microsoft Knowledge Base Article 3088195. Note: This is a detection change only. Customers who have already successfully updated their systems do not need to take any action.